I'm not sure if this helps. I don't run a mining pool. Just a hobonickeler.
When I used 1.1 client I got the error message "WARNING: Checkpoint is too old. Redownload Blockchain. If warning persist contact the Development Team". I deleted the blockchain info, upgraded to 1.2 client, and I still get the same error message.
Should not use 1.1, as of Halloween you will be forked off the main chain. As far as the Warning Checkpoint. That is ok, basically just a notice that the CP needs updated. With each release I update the CP. In some future release I will make it automatic. But that won't be for a while.